Field of the Invention
The invention relates in general to a layer access method, a data access device and a layer access arrangement method, and more particularly to a layer access method, a data access device and a layer access arrangement method that are capable of saving a bandwidth and/or enhancing operating performance.
Description of the Related Art
One's daily life involves various kinds of display devices. For example, one watches television, and uses a mobile phone for communications and a tablet computer for internet access. Accompanied with progresses in multimedia display technologies as well as changes in commercial modes and viewing habits, a same display image may simultaneously include graphics and messages from many different sources. For example, apart from displaying a moving or still image background, a display image may at the same time display moving or still subtitles, diagrams, advertisements or operation interfaces. Since the graphics and messages are from different sources, a data access device is required for accessing required contents from these different sources, and the graphics and messages from these different sources are superimposed on the image background according to a predetermined display sequence. The superimposed image is then displayed on a display panel.
As shown in FIG. 1, assume that a non-rectangular diagram 122 is to be displayed on a background image 110. In a current technique, a corresponding rectangular diagram 120 (including the non-rectangular diagram 122 to be displayed and non-necessary information 124 that need not be displayed) is loaded according to horizontal and vertical start positions (x_st, y_st) and end positions (x_end, y_end) of the non-rectangular diagram 122, and is superimposed onto the background image 110 for display. As such, a large bandwidth may be wasted in loading the non-necessary information and performance is thus reduced. As shown in FIG. 2, assume that a plurality of overlapping diagrams such as a first rectangular diagram 220 and a second rectangular diagram 230 are to be displayed on a background image 210. In a current technique, contents of the first rectangular diagram 220 having a lower display sequence are loaded according to horizontal and vertical start positions (x_st_1, y_st_1) and horizontal and vertical end positions (x_end_1, y_end_1) of the first rectangular diagram 220, and are superimposed onto the background image 210. Next, contents of the second rectangular diagram 230 having a higher display sequence are loaded according to horizontal and vertical start positions (x_st_2, y_st_2) and horizontal and vertical end positions (x_end_2, y_end_2) of the second rectangular diagram 230, and are superimposed onto the first rectangular diagram 220 and the background image 210. As heights of the two rectangular diagrams 220 and 230 overlap, most of the contents of the first rectangular diagram 220 having a lower display sequence are not displayed. The loading procedure of the data that is not displayed results in a bandwidth waste and reduced performance. Further, again referring to FIG. 2, assume that, in a unit of pixels, it is determined whether each pixel position on the background image is to be utilized for displaying pixels of another diagram source. In a current technique, horizontal and vertical positions (x, y) of each pixel position are compared with the horizontal and vertical start positions (x_st_1, y_st_1) and (x_st_2, y_st_2) as well as the horizontal and vertical end positions (x_end_1, y_end_1) and (x_end_2, y_end_2) of the two rectangular diagrams 220 and 230, so as to determine whether the position (x, y) of each pixel falls within ranges covered by the two rectangular diagrams 220 and 230 to further confirm whether the position (x, y) is to display contents included in the two rectangular diagrams 220 and 230. However, such approach performs the above comparison in a unit of pixels, and thus consumes a large portion of computation performance and expends great hardware costs. More particularly, the number of comparisons to be carried out correspondingly increases by a large scale when the quantity of source images gets larger, leading to immense performance and cost consumption.
In view of the above issues of bandwidth waste and unsatisfactory performance as well as the expanding demand of multi-image display, there is a need for an efficient solution that overcomes the drawbacks of the prior art.